JPH01243015A - Projection type display device - Google Patents

Abstract

PURPOSE:To improve the efficiency that the overall device utilizes light, to make a device compact and to obtain large mount of optical output by preventing a decrease in the light utilizing efficiency of a longer part of an optical path with the aid of a light transmitting means which combines convergent lenses to said part. CONSTITUTION:The title device consists of three light valves 42-44 forming an optical image in response to an image signal after projecting a light beam coming out of a field lens 39 and light beams coming out of two light transmitting means 40 and 41. A real image of an emitter in a light source is formed near a central convergent lens 52 by means of a condenser lens and, for example, a convergent lens 50 in the input part of the light transmitting means 40, and a real image of an object near the convergent lens 50 in the input part is formed near a convergent lens 54 in an output part by means of the central convergent lens 52. In this way, the light which the convergent lens 50 and the central convergent lens 52 are trying to emit is converted to the convergent light so that a decrease in the light utilizing efficiency of a longer part of an optical path is prevented. Therefore, the light utilizing efficiency of an optical system is improved, the device is made compact and a large amount of optical output is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a projection display device that irradiates an optical image formed on a light valve with illumination light and projects it onto a screen using a projection lens.

Conventional technology In order to display images on a large screen, an optical image is formed on a relatively small light valve according to the image signal by changing its optical characteristics, and this optical image is irradiated with illumination light and projected onto a screen using a projection lens. A method of enlarging and projecting an image upward has been well known. In this type of projection display device, the resolution of the projected image is almost determined by the resolution of the light valve.
Increasing the intensity of the light source increases the light output, so if a high-resolution light valve is used, a projection type display device with high resolution and high light output can be realized even if the display area is small. Recently, methods using liquid crystal panels as light valves have been attracting attention (for example, 5I086
(Digest, page 375), an example of a conventional configuration of such a projection type display device is shown in FIG.

The lamp 1 emits light containing red, green, and blue color components, and the light emitted from the lamp 1 is converted into nearly parallel light by a condenser lens 2 and a concave mirror 3, and transmitted through a heat ray absorption filter 4. Thereafter, the light enters the color separation means 5. The color separation means 5 includes a flat red reflective dichroic ink mirror 6 and two divided flat blue reflective dichroic ink mirrors 7 and 8 arranged in an X-shape. The red light coming out of the color separation means 5 passes through plane mirrors 9 and 10, and the green light goes straight.
Blue light is a plane mirror 1). 12, and enter corresponding liquid crystal panels 13, 14, and 15, respectively. Optical images are formed on each of the liquid crystal panels 13, 14, and 15 as changes in transmittance according to video signals. liquid crystal panel 13,
The output lights from 14 and 15 are combined into one by the light combining means 16 to form a color image substantially at the position of the green liquid crystal panel 14. This color image is enlarged and projected onto a screen (not shown) by a telescopic projection lens 17. The light synthesis means 16 includes four right angle prisms 1.
This is a prism-type dichroic ink mirror in which parts 8, 19, 20, and 21 are bonded together, and a red-reflecting dichroic multilayer film is deposited on the bonding surface 22.23, and a blue-reflecting dichroic multilayer film is deposited on the bonding surface 24.25. The intersection 26 of the multilayer film is made very thin so that its influence does not appear on the screen.The intersection 27 of the zero color separation means 5 is also projected onto the screen in a blurred band shape, but the F of the projection lens 17 If the number is small, there is no practical problem.

The projection type display device shown in FIG. 5 has a feature that the screen size or the distance from the projection lens 17 to the screen can be easily changed because it has one projection lens. Furthermore, since the color separation means 5 and the light synthesis means 16 have dichroic ink multilayer films intersecting each other in an X-shape, the space required for the optical system is reduced.

Problems to be Solved by the Invention In the configuration shown in FIG. 5, the optical path from the condenser lens 2 to each liquid crystal panel 13, 14, 15 is short for green light and long for red and blue light. Generally, the light emitted from the condenser lens 2 spreads out as the optical path becomes longer, so green light has a high light utilization efficiency, but red and blue light have low light utilization efficiency due to the longer optical path length. When considering the white balance of a projected image, it is necessary to insert an attenuation filter into the green optical path, for example, to achieve an optimal red, green, and blue illuminance ratio. The light use efficiency of the entire device is determined by the light of the color that is the most lacking in the optimal red, green, and blue illuminance ratio, so in the configuration shown in Figure 5, the light use efficiency of the entire device is low and the light output is low. The problem is that it's small. In addition, the light output of the device can be increased by increasing the light output of the light source.
There is a problem in that the larger the light source becomes, the larger the entire device becomes.

The present invention has been made in view of these points, and an object of the present invention is to improve the light utilization efficiency of an optical system and provide a compact projection display device with a large light output.

Means for Solving the Problems In order to solve the above problems, the projection display device of the present invention includes:
A light source that emits light containing color components of three primary colors, a color separation means in which multilayer film surfaces that separate the output light of the light source into light of the three primary colors intersect in an X shape, and a color separation means that passes straight through the color separation means. A field lens into which light enters, two light transmission means into which light that is laterally bent and exits from the color separation means enters, and light output from the field lens and light output from the two light transmission means. three light valves each irradiated with light to form an optical image in accordance with a video signal; and a light combining means made of an X-shaped cross-section of multilayer film surfaces that combine the output light from each of the light valves into one. and a projection lens for receiving the output light from the light combining means and projecting the optical image onto a screen, the light traveling straight through the color separation means going straight through the light combining means, and the field lens projecting the optical image onto a screen. allowing the emitted light to reach the projection lens;
The light transmission means is arranged in an optical path between an input part converging lens arranged at the input end, an output part converging lens arranged at the output end, and the input part converging lens and the output part converging lens. a central converging lens; an input plane mirror that bends an optical path between the input converging lens and the central converging lens; and an input plane mirror that bends the optical path between the central converging lens and the output converging lens. an output side plane mirror, the input part converging lens forms a real image of the light emitting body in the light source near the central part converging lens, and the central part converging lens forms a real image of the light emitting body in the light source near the output part converging lens; A real image of an object near the converging lens is formed, and the output converging lens allows its output light to reach the projection lens.

According to the above structure, a real image of the light emitting body in the light source is formed in the vicinity of the central converging lens by the condensing lens and the input converging lens of the light transmission means, and the central converging lens forms a real image of the light emitting body in the vicinity of the input converging lens. Since the real image of the object is formed near the output converging lens, all light that enters the input converging lens and reaches the central converging lens passes through the output converging lens and is output. The input side plane mirror and the output side plane mirror only bend the optical path within the light transmission means. In this way, the input part converging lens and the central part converging lens convert the light that is about to diverge into convergent light and prevent the light from spreading within the light transmission means, reducing the light utilization efficiency in the long part of the optical path. can be prevented. Next, since the field lens and the output section converging lens allow their emitted light to reach the projection lens, the light utilization efficiency of this part is the same as that of the conventional system. Therefore, by using a light transmission means in combination with a converging lens, it is possible to realize a projection type display device with improved light utilization efficiency.

Embodiment Hereinafter, an embodiment of a projection type display device according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows the configuration of an optical system in an embodiment of the present invention, in which 30 is a light source, 38 is color separation means, 39 is a field lens, 40, 41 is light transmission means, 42, 43 .
44 is a light valve, 45 is a light combining means, 46 is a projection lens, 50 is an input section converging lens, 51 is an input side plane mirror, 52 is a central section converging lens, 53 is an output side plane mirror, and 54 is an output section converging lens. be. In addition, the color separation means 3
8 and photosynthesis means 45 are the same as those used in the conventional example shown in FIG.

The light source 30 includes a lamp 31, a condensing lens 32, and a concave mirror 3.
3 and a heat ray absorption filter 34.
1 emits light containing the three primary color components of red, green, and blue.

Light emitted from the lamp 31 is converted into nearly parallel light by a condenser lens 32 and a concave mirror 33. Strictly speaking, the light rays emitted from the center 36 of the light emitter 35 of the lamp 31 are emitted from the condenser lens 32 in parallel to the optical axis 37. Infrared rays of the light emitted from the condensing lens 32 are removed by a heat ray absorption filter 34. The output light of the light fJ30 enters the color separation means 38 and is separated into red, green, and blue light, the green light enters the field lens 39, and the red and blue lights enter the light transmission means 40 and 41, respectively. incident. The red light exiting the light transmission means 40, the green light exiting the field lens 39, and the blue light exiting the light transmission means 41 enter red, green, and blue light valves 42, 43, and 44, respectively. light valve 42
, 43 and 44 are transmissive liquid crystal panels, which form optical images as changes in transmittance in response to video signals. The output light from the light valves 42, 43, 44 is the photosynthesis means 4
5 into one, substantially the light valve 43
The color image is composited at the position. This color image is enlarged and projected onto a screen (not shown) by a projection lens 46.

The field lens 39 is a plano-convex lens with a plane 47 facing the light valve 43, and when a ray parallel to the optical axis 37 is incident on the field lens 39, the output ray is near the center 49 of the pupil 48 of the projection lens 46. I'm trying to reach it. The reason why the field lens 39 is shaped and oriented in this manner is to prevent spherical aberration from increasing and because surface polishing is relatively inexpensive.

The projection lens 4G is a projection lens with a small angle of view on the light valve side. This is due to the following reasons. In general, light valves have the property that their optical characteristics differ depending on the angle of incidence of the incident light, and when using a normal wide-angle projection lens, the angle of incidence of the principal ray on the light valve increases as you move away from the center of the light valve. Therefore, the image quality may differ between the center and the periphery of the screen. To avoid this, it is recommended to set the half angle of view on the light valve side to 10 degrees or less.

FIG. 2 shows the configuration of the red light transmission means 40, which includes, in order from the color separation means 38 side, an input section converging lens 50, an input side plane mirror 51, a central section converging lens 52, and an output side plane. It is composed of a mirror 53 and an output converging lens 54. The input converging lens 50 is a plano-convex lens with a plane 55 facing the central converging lens 52, and the central converging lens 5
2 is a biconvex lens with the same radius of curvature on both surfaces 56 and 57; the output converging lens 54 is a biconvex lens;
0,52.54 are arranged at equal optical path intervals. In order to bend the optical path at right angles, an input side plane mirror 51 is arranged between the input part converging lens 50 and the central part converging lens 52, and an output side plane mirror 51 is arranged between the central part converging lens 52 and the output part converging lens 54. A plane mirror 53 is arranged. The focal length of the input converging lens 50 is twice the focal length of the central converging lens 52 so that the focal point of the input converging lens 50 is near the center 58 of the central converging lens 52.

The output converging lens 54 is configured so that the light beam exiting from the center 58 of the central converging lens 52 is refracted and reaches the vicinity of the center 49 of the pupil 48 of the projection lens 46 . The reason why the input converging lens 50 is a plano-convex lens and the plane 55 is directed toward the central converging lens 52 is to avoid increasing spherical aberration and because plane polishing is relatively inexpensive. The reason why the central converging lens 52 is a biconvex lens with the same radius of curvature on both surfaces 56 and 57, and the output converging lens 54 is a biconvex lens is also to prevent spherical aberration from increasing.

The blue light transmitting means 41 has the same structure as the red light transmitting means 40.

The operation of the red light transmitting means 40 shown in FIG. 2 will be explained below. Figure 3 shows the projection lens 46 from the lamp 31.
This figure shows the optical system up to this point, and only related optical parts are shown to simplify the explanation. The light transmission means 40 has the following properties.

First, from the relationship between the focal length of the central converging lens 52 and the positions of the converging lenses 50, 52, 54, the real image 61 of the object 60 located near the center 59 of the input converging lens 50 is output by the central converging lens 52. The object 60 is formed near the center 62 of the partially convergent lens 54, and the object 60 and the real image 61 have the same size. Therefore, a ray of light that enters any position of the central converging lens 52 from any position of the input converging lens 50 necessarily enters the output converging lens 54 . Moreover,
The diameters of the beams of light incident on the light valves 42, 43, and 44 are approximately the same.

Second, the focal point of the input converging lens 50 is near the center 58 of the central converging lens 52, and the central converging lens 52
Since there is no refractive power near the center of the lens, the light ray 63 incident on the periphery of the input converging lens 50 parallel to the optical axis 37 passes through the center 58 of the central converging lens 52 and passes around the output converging lens 54. pass. Therefore, when the light beam emitted from the center 36 of the light emitter 35 of the lamp 31 is refracted by the condenser lens 32 and exits parallel to the optical axis 37, the condenser lens 32 and the input converging lens 50 A real image 64 of the light emitter 35 of the lamp 31 is located at the center 5 of the central converging lens 52.
Formed around 8.

From the above, if the effective area of the central converging lens 52 is larger than the real image 64, all the light incident on the input converging lens 50 will exit from the output converging lens 54, and no light will be inside the light transmitting means 40. It can be seen that there is no loss due to expansion. Therefore, compared to the conventional configuration shown in FIG. 6, the light utilization efficiency of red and blue light becomes higher, and as a result, the light utilization efficiency of the entire device becomes higher.

The light rays emitted from the center 36 of the light emitter 35 of the lamp 31 pass through the field lens 39 with the green light passing through the field lens 39, and the red and blue lights passing through the light transmission means 40, 41, respectively, to the pupil of the projection lens 46. It reaches near the center 49 of 48. That is, a real image of the light emitting body 35 of the lamp 31 divided into red, green, and blue is formed near the pupil 48 of the projection lens 46. In Figure 3,
The case of red light is shown. Therefore, light valve 4
The light emitted from 2°43.44 reaches the screen efficiently. In addition, in the configuration shown in FIG. 2, since the optical path length from the input section converging lens 50 to the output section converging lens 54 can be freely selected, the flat mirror 5 for bending the optical path is used.
1.53 can be placed in sufficient space.

Next, a description will be given using a specific numerical example.

The display dimensions of the light bulb are 40mm x 5Q, the projection lens 46 has a focal length of 150fi, the brightness is F2.5, the field lens 39 has a focal length of 170mm, the input converging lens 50 has a focal path of M130th, and the central converging lens 52
has a focal length of 65tm, and the output converging lens 54 has a focal length of g.
It is lBOn. In the configuration shown in FIG. 5, the illuminance immediately before the red light valve 13 was approximately 50% of the illuminance immediately after the color separation means 5, but in the configuration shown in FIG. The illuminance immediately before the color separation means 42 was approximately 75% of the illuminance immediately after the color separation means 3 days, and an improvement in light utilization efficiency was clearly recognized.

Next, other embodiments of the present invention will be described.

Input converging lens 50 of light transmission means 40 shown in FIG.
does not have to be a plano-convex lens. FIG. 4 shows an example of this case, in which the input converging lens 65 is a biconvex lens with a surface 66 of small curvature facing the central converging lens 52. Generally, when a spherical lens has a small F number, spherical aberration becomes large, and the spread of light cannot be ignored. In this case, a biconvex lens in which the radius of curvature of the surface 66 facing the central converging lens 52 is approximately twice the radius of curvature of the other surface has less spherical aberration than a plano-convex lens. In addition, the input section converging lens 50 shown in FIG. Scum converges in the center 52. At least one lens in at least one of the output converging lenses 54
By including two aspherical surfaces to suppress the occurrence of various aberrations in the light transmitting means 40, it is possible to further reduce the loss caused by the spread of light within the light transmitting means 40. this is,
The same applies to the light transmission means shown in FIG.

In the configuration shown in FIG. 1, the field lens 39 is a plano-convex lens, but a spherical lens of another shape or a lens with an aspherical surface on at least one surface may be used to increase the illuminance of the periphery relative to the center of the screen. It is also possible to optimize the ratio. In this case, it is advantageous in terms of aberrations to face the light valve 43 with a surface with a small curvature.

In the configuration shown in FIG. 2, the input converging lens 50 is a plano-convex lens, and the relationship between the focal length of the central converging lens 52 and the positions of the converging lenses 50, 52, and 54 is defined, but there is no need to be particular about this. , by making some changes, you can adjust the illuminance ratio of the peripheral area to the center of the screen, red, green,
It is also possible to optimize the blue illuminance ratio.

In Figure 1, an example is shown in which a liquid crystal panel is used as the light valve 42, 43, 44, but any material that can form an optical image according to the video signal by changing its optical characteristics, such as an electro-optic crystal, can be used as the light valve. be able to. Although FIG. 1 shows an example in which a prism-type dichroic ink mirror is used as the light combining means 45, if high resolution is not required, a flat dichroic mirror may be used in an X-shape like the color separation means 38. A cross can be used. In either case, the same functions and effects as in the above-described embodiments can be obtained.

Effects of the Invention As described above, according to the present invention, a light transmission means combined with a converging lens is used in a long part of the optical path to prevent a decrease in light usage efficiency in that part, so the light usage of the entire device is improved. Efficiency can be improved, thereby making it possible to provide a projection type display device that is compact and has a large light output, which has a very large effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing the configuration of a projection type display device according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a light transmission means used in the projection type display device shown in FIG. 1, and FIG. 3 4 is a route map for explaining the operation of the light transmission means shown in FIG.
This figure is a schematic block diagram showing the structure of a light transmission means in another embodiment of the present invention, and FIG. 5 is a schematic block diagram showing the structure of a conventional projection type display device. 30... Light source, 38... Color separation means,
39...field lens, 40.41...
... Light transmission means, 42.43.44 ... Light valve, 45 ... Photosynthesis means, 46 ...
...Projection lens, 50...Input section converging lens,
51... Input end plane mirror, 52...
Central part converging lens, 53... Output side flat mirror, 54... Output part converging lens. Name of agent: Patent attorney Toshio Nakao, 1 person\Ku Hide~) C%1 Regret

Claims (10)

[Claims] (1) A light source that emits light containing color components of three primary colors, a color separation means in which multilayer film surfaces intersect in an X shape for separating the output light of the light source into light of the three primary colors, and the color separation means a field lens into which light traveling in a straight line is incident; two light transmission means into which light which is laterally bent and emitted from the color separation means is incident; and light emitted from the field lens and the two
The three light valves are irradiated with the light emitted from the three light transmission means to form an optical image according to the video signal, and the multilayer film surface that combines the output light from each of the light valves into one is an X-shaped surface. the light combining means crossed in the shape of a shape, and a projection lens for receiving output light from the light combining means and projecting the optical image onto a screen, the light traveling straight through the color separation means traveling straight through the light combining means. , the field lens allows its emitted light to reach the projection lens, and the light transmission means includes an input section converging lens disposed at the input end, an output section converging lens disposed at the output end, and the input section. a central converging lens disposed in an optical path between the converging lens and the output converging lens; an input plane mirror that bends the optical path between the input converging lens and the central converging lens; an output plane mirror that bends an optical path between a central converging lens and the output converging lens, and the input converging lens forms a real image of the light emitting body in the light source in the vicinity of the central converging lens. The central converging lens forms a real image of an object near the input converging lens near the output converging lens, and the output converging lens causes its output light to reach the projection lens. A projection display device characterized by: (2) The projection display device according to claim (1), wherein the light emitted from the light source is close to parallel light. (3) The input section converging lens, the central section converging lens, and the output section converging lens are arranged at approximately equal optical path intervals, and the focal length of the input section converging lens is approximately twice the focal length of the central section converging lens. 2. The projection type display device according to claim 1, wherein the focal point of the input converging lens is located approximately at the center of the central converging lens. (4) The input part converging lens is a lens whose surface with small curvature is directed toward the central part converging lens (
1) The projection type display device described above. (5) The projection type display device according to claim (1), wherein the input converging lens is a plano-convex lens with a plane facing toward the central converging lens. (6) The projection type display device according to claim (1), wherein the central converging lens is a biconvex lens having the same radius of curvature on both sides. (7) The projection type display device according to claim (1), wherein the field lens is a lens whose surface with a large curvature is directed toward the color separation means. (8) The projection type display device according to claim (1), wherein the field lens is a plano-convex lens with a convex surface facing the color separation means. (9) The projection type display device according to claim (1), wherein the output converging lens is a biconvex lens. (10) The projection display device according to claim (1), wherein at least one of the field lens, the input converging lens, the central converging lens, and the output converging lens includes at least one aspherical surface. .